Several Illinois environmental groups have filed a complaint against Midwest Generation for allegedly violating solid waste and water pollution regulations at the company's four remaining Illinois coal plants. The groups contend that contaminants such as arsenic leak from coal ash ponds around the plants and then may enter into local water supplies.

A Midwest Generation spokesman told the Chicago Tribune that the company would defend "our operations" against environmental groups the company sees as determined to shut down the coal plants. Amid pressure from environmental groups and community organizations, Midwest Generation shut down its Fisk and Crawford coal-fired power plants this year that had operated on Chicago's Southwest Side.